(1) Field of the Invention
The present invention relates to a shipping container for accommodating silicon wafers and the like.
(2) Description of the Prior Art
A conventional shipping container, although it is not illustrated, comprises: a storage case having an opening on the top; an inner receptacle for the correct alignment of silicon wafers (to be abbreviated as wafers hereinbelow) therein; a top door being fitted on the top opening of the storage case with a gasket in between to cover the inner receptacle for alignment; and a wafer pressing plate attached on the inner top surface of the top door. The thus configured top opening type shipping container holds a plurality of wafers placed upright in the inner receptacle for alignment, and is transported as appropriate.
Recent years, in order to reduce the development cost and manufacturing cost, unified standardization of wafers is in progress. This has been followed by a proposal of use of internationally standardized shipping containers. Such proposals of standardization have been made in view of development of large-sized wafers (transition to 300 mm or greater diameter wafers in the near future), which need improved positioning and precision alignment (to allow the unloader to perform high-speed accessing), as well as in view of reduction of various costs and to deal with development of the large-sized system and also automation.
Such a shipping container under the unified standards, although it is not shown, comprises: a storage case opening to the front; a Front-Opening Interface Mechanical Standard door (to be abbreviated as FIMS door hereinbelow) which opens and closes off the front opening of the storage case; a plurality of fitting slots formed on the inner peripheral surface of the storage case; and a latching mechanism which enables engaging claws to mate the fitting slots when the FIMS door is attached and to disengage the mating of the engaging claws with the fitting slots when the FIMS door is removed.
Such a front opening type shipping container accommodates plural wafers arranged vertically and this shipping container is transported from a semiconductor manufacturer to an IC manufacturer where it is automatically set in various processors. Subsequently, the latching mechanism is automatically disengaged by a working robot so that the FIMS door is automatically removed from the storage case and then the plurality of wafers are successively taken out from the storage case by the unloader in an automatic manner.
The prior art documents for configurations of this type include Japanese Utility Model Application Laid-Open Sho 63 No. 82,788, Japanese Utility Model Application Laid-Open Sho 63 No. 166,948, Japanese Patent Application Laid-Open Hei 8 No. 279,546 and Japanese Patent Application Laid-Open Hei 9 No. 107,025.
The shipping containers satisfying the unified standard are thus configured and are effective in improving the positioning precision, reducing various costs and promoting automation, but still give rise to a problem with respect to transport. Specifically, a shipping container of the unified standard is effective enough for in-plant transport between the processing sites but having only a FIMS door cannot provide high enough strength to ensure sufficient confinement for long distance transport using airplanes or trucks from a semiconductor manufacturer to an IC manufacturer because the container is exposed to various external environments (including pressure variations, vibrations during flight, etc.). Resultantly, the wafers maybe polluted with particles or subject to organic pollution, which may be accompanied by the entrance of the external air, so that there is the fear that the wafers cannot be retained in high enough quality.